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991.
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994.
The Reaction Activity of Aromatic Carbonyl Compounds with Diphenylphosphine Oxide Studied by 31P NMR
Jinyun Zheng Xiangming Feng Yujian Yu Xiaomin Zhen Yufen Zhao 《Phosphorus, sulfur, and silicon and the related elements》2013,188(8):1080-1087
Abstract A series of α-hydroxyphosphine oxides were prepared by the reactions of diphenylphosphine oxide and aromatic carbonyl compounds and characterized by 1H NMR, 13C NMR, 31P NMR, FT-IR, ESI-MS, and HR-MS spectra. The reaction rates and experimental conditions of aromatic aldehydes and aromatic ketones were obviously different due to the activity of their carbonyls. The different substituents of the aromatic aldehydes affected the reaction rate too, and the quantitative reactivity of their substituent conformed to the Hammett equation. The results were confirmed by 31P NMR spectroscopy. 相似文献
995.
Considering intrinsic properties of conjugated polyfluorenes and special functions of porous polymers, synthesis of fluorinated porous poly(spirobifluorene) via direct C?H arylation polycondensation is explored. Owing to the contorted structure and cross-linking nature, the obtained polymer FPSBF shows permanent porosities with Brunauer–Emmett–Teller specific surface area up to 700 m2 g?1 and exhibits a narrow pore size distribution with the dominant pore size at about 0.63 nm, which is more suitable for adsorption of small gas molecules. Based on the measured gas physisorption isotherms with pressure up to 1.13 bar, the obtained polymer shows good uptaking capacities for hydrogen (1.30 wt% at 1.0 bar and 77 K) and methane (4.80 wt% 1.0 bar and 273 K). Moreover, FPSBF has significant adsorption selectivity for CH4 against N2 and the estimated ideal adsorption selectivity ratio is up to 30/1 at 1.0 bar and 273 K, which makes the material possess potential application in gas separation. 相似文献
996.
The free radical copolymerization of acrylic acid (M1) with p-chloromethylstyrene (M2) in dioxane and in the presence of α,α′-azobisisobutyronitrile (AIBN) at 65°C is reported. Copolymer compositions of six copolymer samples obtained from feed ratios of M1:M2 = 95.2:4.8 to 21.4:78.6 were determined by 1H-NMR. The reactivity ratios of AA/p-CMS copolymerization system calculated by the F-R method were r 1 = 0.50 ± 0.06 and r 2 = 1.52 ± 0.15, almost the same as r 1 = 0.43 ± 0.21 and r 2 = 1.31 ± 0.14 by the extended K-T method. On the basis of the reactivity ratios of two monomers, the sequence length distribution in the AA/p-CMS copolymers was obtained. For f2 = 4.77%, the monomer unit of p-CMS is individually separated in the chain of AA; for f2 = 35.53%, the alternating tendency prevails and a large number of mono-sequences are formed. The number-average ( n) and weight-average ( w) molecular weights were determined by gel permeation chromatography. The effect on molecular weights of feed composition is also discussed. In the presence of constant initiator concentration, the gradual increase in the ratio of M2:M1 (from14.7:85.3 to 78.6:21.4) was accompanied by a decrease in molecular weights ( n from 11907 to 3961). 相似文献
997.
Langang Niu Ramaswamy Nagarajan Dingsong Feng Lynne A. Samuelson 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(12):1983-1990
Main‐chain thermotropic liquid‐crystalline polyesters containing rigid biphenyl mesogens and flexible spacers were synthesized by chemo‐enzymatic route. The enzyme‐catalyzed polymerization showed high regio‐ and chemo‐ selectivity, and is environmentally friendly. The resulting polyesters were characterized with 1H‐NMR, 13C‐NMR, gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and polarized light optical microscopy (POM). 相似文献
998.
Atom transfer radical polymerization (ATRP) of MMA was conducted using 2‐(4‐chloromethyl‐phenyl)‐benzoxazole as initiator, CuCl as catalyst, and PMDETA as ligand. The results show that the polymerization is a first order reaction with respect to monomer concentration. The polymerization displayed living character as evidenced by a liner increase of monomer weight with conversation and a relatively narrow distribution (Mn/Mw range from 1.30 to 1.45). The structure of PMMA was analyzed by 1H‐NMR and proved the polymerization could be controlled to some degree. The optical property of the initiator was well preserved in the resulting PMMA, and the end‐functionalized PMMA exhibited fluorescent emission at 360 nm whether in DMF solution or in film state. 相似文献
999.
Wen-Ying Xu Zhong-Hua Pei Da-Gang Zheng Li-Ren Lou Cheng-Yue Gao Yue-Sheng Wang 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(9-11):1109-1117
Europium triundecylenate, Eu(UA)3, and terbium triundecylenate, Tb(UA)3, were prepared by the method described in our previous paper. Either Eu(UA)3 or Tb(UA)3 was dissolved in methacrylic acid (<20%) and copolymerized as a crosslinker with methyl methacrylate (>80) by bulk polymerization in molds made of two glass plates. The fluorescence spectroscopy of these Eu- or Tb-containing polymers under ultraviolet/visible excitation light was investigated. The fluorescence spectroscopy of solutions of Eu(UA)3 or Tb(UA)3 in methacrylic acid was measured and compared with that of the solid-state Eu- or Tb-containing polymers. The fluorescence excitation and emission spectra of the solutions and polymers showed the characteristic features of free Eu3+ or Tb3+. The lifetime fluorescence of the solutions and polymers with Eu3+ are also included. 相似文献
1000.
AbstractNew insights for the effects of organic solvent polarities and solvent-monomer interactions on the radical copolymerization for an important copolymer, poly(acrylonitrile-co-methyl acrylate) (PAN-co-MA), were provided in this research. Solvents, dimethylformamide (DMF), dimethylacetamide (DMAc) and dimethyl sulfoxide (DMSO), were used as reaction media. The polarity of these solvents was in the sequence of DMAc?<?DMF?<?DMSO. By studying the reactivity ratios of AN and MA, the triad fractions of the resultant copolymers, the interactions between monomers and solvents, and the compositions of copolymers at various conversions, we concluded that the solvent polarity had minimal influence on the copolymerization of AN and MA, while the solvent-monomer interactions played important roles. The interactions between monomer-monomer, monomer-solvent, and solvent-solvent, were calculated based on quantum chemistry methods. Both theoretical calculations and experimental results suggested that AN and MA in DMSO tended to aggregate locally, while they could be homogeneously dissolved in DMAc and DMF. The interactions between solvent and monomers could cause local monomer concentration variations, or ‘bootstrap’ effect, which is one of the critical factors affecting the copolymerization process of AN and MA and the chemical structures of the resultant polymers. 相似文献